1819.] Acids, Alkalies, and their Compounds. 349 



In the mutual action of acids and salifiable bases with regard 

 to saturation, the simple rule will be, that in all cases an acid 

 will saturate that quantity of a base, the radical of which is in 

 the equivalent weight to the radical of the acid. And the' quan- 

 tity of oxygen in the salt will be that which constitutes the usual 

 proportion of that element to the radical of the acid. 



The capacity of saturation in the different acids and bases, in 

 their reciprocal action, has been proposed as a measure of the 

 force of affinity which they exert, those acids being inferred to 

 have the strongest attractions to the salifiable bases, which in 

 the smallest quantities saturate a given weight of these bases ; 

 and the same rule being applied to the attraction of the bases to 

 the acids. The capacity of saturation, however, depends alto- 

 gether on a different cause, on the relations of the more remote 

 elements to each other, and not any direct action of acid and 

 base. A larger quantity of barytes is necessary to saturate a 

 <nven Wfcfehtf Of the different acids than of potash, not because 

 barytes has a weaker action on acids than potash has, but 

 because the combining weight of barium is greater than that of 

 potassium ; and it combines, therefore, in larger quantity with 

 the radicals of the acids ; and conversely, a larger quantity of 

 sulphuric than of carbonic acid is necessary to saturate a given 

 weight of the different bases, not because its affinity to them is 

 less powerful, but because the combining weight of sulphur is 

 higher than that of carbon. And were the doctrine of the 

 influence of elective affinities, independent of the operation of 

 external forces on chemical attraction established, barytes 

 would be considered as exerting a more powerful attraction than 

 potash to sulphuric acid, from the attraction of barium to suphur 

 being stronger than that of potassium to sulphur. From the 

 test, however, of the strength of attraction to be found in the 

 capacity for saturation, the attraction of potassium must be 

 inferred to be superior to that of barium to sulphur ; and the 

 results of double decomposition of what are called their saline 

 compounds must be ascribed, in conformity to Berthollet's doc- 

 trine, to the influence of the force of cohesion, this force acting 

 more powerfully on the ternary compound of barium, sulphur, 

 •md oxygen, than on that of potassium, sulphur, and oxygen. 

 These Views apply to all the other cases of decomposition in 

 saline combinations. 



Supplement to the preceding Paper. 



Sir II. Davy has stated some experiments in opposition to the 

 t vidence of water being procured from the action of muriatic 

 acid gas in metals.* On these, so far as they refer to the expe- 



Xhcv follow indeed necessarily from flic relations in Ihc combining xvc-ighU of lUtt 

 elements, ivlicn tlirsc are considered M in simultaneous c'Jtnbi'tulion.- 

 • I'ltiJobouliical Transition-, for 1818, Parti, 



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